Question

Calcule o 10° termo da P.A (100,80,60)

Answer 1

$PA (100,80,60)\\\\ a_{10}=?\\ a_1=100\\ n=10\\ r=80-100=-20\\\\ a_n=a_1+(n-1)*r\\\\ a_{10}=100+(10-1)*(-20)\to \\ a_{10}=100+9*(-20)\to \\ a_{10}=100-180\to \\ a_{10}=-80\\\\\\ PA(100, 80, 60, 40, 20, 0, -20, -40, -60 , -80)$